Garre’s osteomyelitis is a rare chronic inflammatory disease with reactive peripheral bone formation due to low-grade local infection. Here, we present a 12-year-old female with chronic osteomyelitis and proliferative periostitis with no definite source of infection, such as caries or periodontitis. The patient had a history of 4-5 hospitalizations with the same symptoms intermittently over the previous two years at the hospital which referred her to our hospital. The patient had undergone a biopsy at the referring hospital, and she was referred to our hospital with a histopathological diagnosis of osteoid osteoma. Physical examination showed a unilateral swelling in the right mandible at admission to our hospital. Since we could not exclude the diagnosis of bacterial osteomyelitis, antibiotics were continued. Periapical radiography, magnetic resonance, computed tomography, and clinical features supported the diagnosis of Garre’s osteomyelitis, so antimicrobial therapy was discontinued. Her biopsy materials were re-examined by the pathologist at our hospital, and Garre’s osteomyelitis was considered. Non- steroidal anti-inflammatory drugs were started. We added colchicine treatment because she failed to achieve remission, and normal facial symmetrical morphology was not achieved in the two-month follow-up period. However, the symptoms regressed within one year, and the swelling disappeared.